This invention relates to electronic musical instruments, and more particularly to the envelope control automatic performance tone production in an electronic musical instrument which carries out automatic performances such as automatic bass, chord and arpeggio performances.
U. S. patent application No. 825443, filed Aug. 17, 1977, and U.S. patent application No. 952098, filed Oct. 17, 1978, both assigned to the same assignee as the present case, disclose a technique wherein automatic bass or arpeggio tone production rhythm patterns timings are stored in a read-only memory (hereinafter referred to merely as "a ROM" when applicable), and are read out according to the tempo signal. In these prior inventions, the pattern data stored in the ROM include only such data as indicate the pitches of automatic performance notes, and the envelopes of the automatic performance tones are not controlled in accordance with patterns; that is, the envelopes are shaped in a predetermined characteristic. Accordingly, in the case of using an envelope waveform having a decaying tail an envelope of a tone tends to rise before an envelope of an immediately preceding tone is sufficiently decayed. This tendency is increased as the time intervals of the automatic performance tone productions become short. Thus, the successively produced tones give an impression that they are not sufficiently separated from one another.